Fire extinguishing apparatus



Aug. 24, 1943. H. c. KENDALL ET AL ,5

FIRE EXTINGUISHING APPARATUS Filed Aug. 15', 1942 Fig.1

Patented Aug. 24, 1943 1 2,327,528 H FIRE EXTINGUISHING APPARATUS Horace Clayton Kendall and Howard G. Freeman,

7 assignors to, Rockwood Sprinkler Company, Worcester, Mass., a oorpo- Worcester, Mass,

ration of Massachusetts APDIication-August-H, 1942, Serial No, 454,896

8, Claims. I (01. 169-3? The present invention relates to improvements in protective caps or covers for spray or fogproducing nozzles or nozzle heads employed in fire extinguishing'systems, and more particularly to blow-olf caps, so called, which are adapted to be blown off automatically upon the discharge of fluid from the nozzle enclosed'therein.

In fire extinguishing systems which employ nozzle heads of the type which emit a fine spray or fog through small openings, it is frequently necessary to protect the heads against corrosion and coating or incrustation arising from the presence of corrosive vapors ortarry or dirtladen vapors. in thevicinity of'the heads.

Toprovide this protection, we propose to furnish protective caps or enclosures to be blown off or other-wise disposed of automatically when operationof the system is necessary. The provision of such caps or: enclosures which will be dependable in operation presents a number of d fi lt e however, While itjrnight be supposed thatfrangible covers. which woul'dshatter under internal pressure might be employed, such covers. have been found unsatisfactory because the material often breaks in a way to leave fragments in place, which distort the fog pattern or destroy its fog-like character, Caps which are held in place by fusible links, thermoplastic. seals, or

other devices dependent on a rise in ten'lperaturev to release the cap, do, not afford a solution to the problem, for one reason because of their sluggish response due to the mass of the parts.

In the case of a slip-on cover, which is intended to be blown off intact by a rise in pressure within the cap upon the discharge of fluid from the nozzle head, it is difilcult to provide a freely sliding,

connectionbetween the cap and the fixed portion of the nozzle while maintaining a fluid tightseal Since most sprinkler systems employing fog or spray nozzles are of the dry pipe type, the pipes must be rid of air in advance of the enterin: water, with the result thatair is first dis charged from the nozzle heads When the system goes into action. blow-01f cap be so designed as; to be blown off by the escaping air, rather than by the water that.

follows, in order that advantage may be taken of the expansion, of the air, after the pressure has built up sufficiently, to blow the. cap off forcibly, Since the fiuid'fiow through a fog or spray type nozzle is relatively small as compared to the conventional sprinkler head, it is evident that leakageat the capcould in many cases prevent, the required; build-up in pressure, with conse- It is highly desirable that a.

quent failure nozzle.

- The present invention therefore has as its ob; ject the provision of a protective enclosure or of the cap to be blown clear of the cover for spray and fog-producing nozzles, which will eifectively seal the nozzle therein against dust, deposits, and corrosive vapors, yet which will automatically be blown entirely ofi without fail upon a rise'in internal pressure.

With this and other objects in View, a feature of the present invention involves the provision of a protective enclosure for a spray or fog nozzle head, including an enclosing shell or cover adapted to be blown off upon a rise in internal pressure caused by fluid discharge from the nozzle, wherein a slidable, sealing connection between cover and base is afforded through the provision of sealing means received in a peripheral groove in, one of the members. i

More specifically, the invention contemplates the provision'of a slidable connection formed by one or more grooves formed in the periphery of the base portion of the enclosure, the grooves being filled with a viscous fluid or grease to provide a substantially fluid-tight but freely sliding connection between cover andbase to permit free axial movement of the cover Without risk of jamming or canting when the pressure behind the cap rises sufficiently.

In the drawing'illustrating the invention in its preferred embodiment, Figure 1 is a side view, partly broken away and partly in section, of the protective enclosure, with a fog nozzle head of typical construction indicated in outline there- I within; and Figure'Z is a fragmentary sectional view on a somewhat larger scale of the sealing and sliding connection between the cover and the base, i

A conventional form of fog nozzle head. employed in fireextinguishing systems is indicated at 4, the nozzle being provided with a plurality of ports or openings, not shown, through which, when the nozzle is in operation, thewater is emitted in the form of impinging streams to generate a, fine mist or fog. The end of the supply pipe shown at. 6, this pipe being normally filled with air in. accordance with the usual practise: in 'dry pipe systems. The admission of water; to the supply pipes is controlled by a master valve which is opened either manually or detection of fire or rapid end, the cover is substantially cylindrical, having an inside diameter substantially that of the outside diameter of the finished surface Id of the rim to provide slidable contact between the parts. i

The cover is yieldingly held inplac'e on the base by means of light spring clips which snap over an inwardly extending bead 22 formed adjacent the open end of'the rim l2. The springs are shaped in relation to the bead to maintain the cover in position on the base with the edge of the cover against the shoulder l6. v

To provide a fluid-tight connection between the cover and the base, which will nevertheless permit the coverto slide freely in an axial direction, annular grooves 26 are provided in the periphery of the rim 1 2. The grooves contain sealing means 28 which may be either resilient, such as a packing material, or fluid, for example a grease or other viscous or semi-viscous non-drying liquid.

Grease or a similar material has been found particularly effective, as it serves both as a seal and as a lubricant for the sliding surfaces. Furthermore it maintains a protective coating over these surfaces and at the exposed edges'to prevent corrosion of. the parts. This latter factor is highly. important, since any corrosion or pitting would give rise to sticking and consequent faulty operation of the cap. The use of afluid typg seal likewise simplifies the installation and main tenance of the caps, since the caps may readily beslipped into place Without catching.

Normally, the parts remain in the position illustrated in Figure 1, with the spring clips holding the cover in positionagainst displacement by vibration or moderate impact. By reason of the tight sealing engagement afforded by the grease or other sealing means contained in the grooves 26, not only fine dust, but also harmful vapors are kept from the nozzle and its passages, and from the interior of the empty supply pipe.

If, however, operation of the system for fire extinguishing purposes becomes necessary at any time, the cover I8 will be promptly blown off without fail before the discharge of water from the nozzle takes place. Upon opening the control valve, the rush of water into the empty supply pipe results in rapidly building up air pressure within the pipe and likewise within the cover 18. In view of the substantial area of the relatively large diameter base, ample force is soon available to start the cover in motion, freeing the springs from the bead 22.

Due to the lubrication afforded by the grease or other sealing material in the grooves and on the opposing surfaces of cover and base, thecover slides freely over the rim. The grease or its equivalent likewise provides a seal'against leakage of the trapped air, which would allow Water to reach and be discharged from the nozzle before complete removal of the cap occurred. The pressure of this trapped air, built up by the advancing water to the point where the cap has started in motion and freed the retaining springs 20 from the bead 22, expands as the cap advances. Movement of the cap is assisted by a compressionsoon as retaining clips 20 are freed, but likewise exerts a force tending to maintain the outerend of the cap in axial alignment with the axis of the base and prevent any tendency of the cap to cant at an angle.

In view of the high velocity with which the caps blow off when a system employing these caps goes into operation, a strong chain'36 is preferably connected between the cover and some firm point of attachment, placed to insure that the released cover will not interfere with the fog or spray pattern.

While the invention has been illustrated and described as making use of a grease or other viscous fluid in the grooves as the sealing 'means, it is evident that a non-fluid means may be used in the grooves, either with or without a sealing and coating fluid or grease. 1 I

Having thus described our inventiomwe claim:

1. In a dry-pipe fire extinguishing system comprising a nozzle head and a supply pipe normally I free of water, a protective enclosure for said head, comprising a base for supporting the head, a cover cooperating with the base to enclose the head and adapted to be blown off upon a rise in internal air pressure occasioned by the admission. of water to the supply pipe, the base and cover having portions adapted to fit one within the other with adjacent surfaces in axially slidable relation, one of said surfaces having a peripheral I groove formed therein, the groove being covered a by the other of the adjacent surfaces when the cover is in place over the base, and means within' 7 the groove providing a sealing and slidable connection between the cover and the base.

2. A protective enclosure for a fire extinguish ing nozzle head, comprising a base for supporting the head, a cover cooperating with the base to enclose the head andadapted to be blown off upon a rise in internal pressure occasioned by 'dis-' charge of fluid from the head, the cover having a straight-walled portion adapted to fit over the periphery of the base with adjacent surfaces in axially slidable relation, an annular groove in upon a rise in internalpressure occasioned by the discharge of fluid from the head, said cover having a cylindrical portion adapted to fit over the rim in axially slidable relation thereto, annular grooves in the periphery of the rim adapted tob e covered when the cover is over the rim, and viscous means within the. grooves to provides.

sealing and slidable connection between the cover and the base.

4. A protectiveenclosure for a fire extinguishing nozzle head, comprising a base provided'with a cylindrical rim, a cover cooperating with the base to enclose the head and adapted to be blown off upon a rise in internal pressure occasionedby,

the discharge of fluid from the head, said'oover having a'cylindrical portion adapted to 'fit over The other end of the springv The spring thus, not only serves to accelerate the blowing oil ofv thecap as V bead portion, a cover cooperating with the base to enclose the head and adapted to be blown ofi upon a rise in internal pressure occasioned by the discharge of fluid from the head, said cover having a cylindrical portion adapted to fit over the rim, annular grooves formed in the periphery of the rim and adapted to be covered when the cover is over the rim, means Within the grooves to provide a sealing and slidable connection between cover and base, and spring fingers carried by the cover and adapted to engage the bead portion of the rim to secure the cover yieldingly to the base.

6. A protective enclosure for a fire extinguishing nozzle head, comprising a base provided with a cylindrical rim, a cover cooperating with the base to enclose the head and adapted to be blown off upon a rise in internal pressure occasioned by the discharge of fluid from the head, said cover having a cylindrical portion adapted to fit over the rim, annular grooves formed in the periphery of the rim, means within the grooves to provide a sealing and slidable connection between the cover and the base, and means connecting the cover to a fixed point to limit the flight of the cover upon disconnection from the base.

7,, A protective enclosure for a fire extinguishing nozzle head, comprising a base provided with a cylindrical rim, a cover cooperating with the base to enclose the head and adapted to be blown off upon a rise in internal pressure occasioned by the discharge of fluid from the head,

said cover having a cylindrical portion adapted to fit over the rim, annular grooves formed in the periphery of the rim, means within the grooves to provide a sealing and slidable connection between the cover and the base, means yieldingly retaining the cover on the base against axial displacement, and resilient means tending to urge the cover axially from the base.

8. A protective enclosure for a fire extinguishing nozzle head, comprising a base provided with a cylindrical rim, a cover cooperating with the base to enclose the head and adapted to be blown off upon a rise in internal pressure 00- casioned by the discharge of fluid from the head,

said cover having a cylindrical portion adapted to fit over the rim, annular grooves formed in the periphery of the rim, means within the grooves to provide a sealing and. slidable connection between the cover and the base, and resilient means tending to maintain the outer end of the cap in axial alignment with the axis of the base. I-I. CLAYTON KENDALL. HOWARD G. FREEMAN. 

